Eels use electricity to remote control prey movements

ZAP! Zap! Electric eels are well known for shocking their prey with 600-volt blasts. But the way they orchestrate their attack is more sophisticated than anyone thought.

It turns out the animals use one shock pattern to find their prey and another to paralyse it.

Eels in the wild emit a barrage of electric pulses into the water to disable nearby fish. To investigate, Kenneth Catania at Vanderbilt University in Nashville, Tennessee, placed fish in an eel tank and studied what happened to their nervous systems and muscles as the eel electrocuted them.

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Catania found that when the eel intended to disable the fish, the series of pulses was timed to precisely mimic the pattern of motor neuron signals that causes the animal’s muscles to contract. Within 3 milliseconds, the signals effectively induced a full-body muscle spasm, paralysing it completely (Science, doi.org/xkq).

He also discovered that the eel has another shocking strategy. If it can’t see its prey, in murky water or rocky environments, for example, it emits a different, high-voltage, two-pulse pattern. This makes the fish twitch uncontrollably, not only telling the eel that a snack is close at hand, but giving away its exact position. The eel can then move in for the final attack.

That eels evolved not only to disable but also flush out their prey is a surprise, says Jason Gallant at Michigan State University in East Lansing. “This is an immensely interesting and important finding for electric-fish biology.” He wonders if other electrogenic fish do this, too.

This article appeared in print under the headline “Nowhere to hide&colon; electric eels use shocks to flush out prey”